I have a tumor on my left breast and it doesn`t hurt. Does that mean that I have cancer?

See a Doctor. Any new lump in the breast should be a cause for concern, best handled by seeing your gyne or primary care doctor. The only definitive means of diagnosis is a biopsy. While most cancers are not painful, it is not a reliable finding. Hopefully, your doctor will be able to alleviate your concern or refer you to a breast center/surgeon for definitive evaluation. I hope its a false alarm.